Zebra mussels do not have many natural predators in North America. But, it has been documented that several species of fish and diving ducks have been known to eat them. 
Generally zebra mussels are small averaging about a half to one inch long. Two inches is approximately the maximum size. Their life span is four to five years. 
The USGS focus is to document the zebra mussel's geographic distribution and to learn as much as possible about its behavior and biology.
It is generally agreed upon by scientists that zebra mussels entered the Great Lakes from ballast water discharged by large ocean-going vessels from Europe. Ballast water is used to keep ships stable in the water.
A zebra mussel is a type of mollusk, which also include a wide variety of organisms such as squids, octopuses, snails, oysters, scallops, and clams. Generally, zebra mussels live for four to five years and average about an inch in length.
They are primarily algae feeders. They feed by filtering the water through a siphon -- up to a liter per day. This is why they like the insides of pipes so well: there is a constant supply of water and food flowing by them. 
Mussels are also called "bivalves." This means they have two shells or valves (a right valve and a left valve). The zebra mussel gets its name because of the dark, striped pattern on each valve.
One of the most well documented impacts is that on our native mussels. Zebra mussels anchor themselves by the thousands to native mussels making it impossible for the native mussel to function.
The scientific name is Dreissena polymorpha.
There are many methods that have been investigated to help control zebra mussels. They are listed below in no particular order. Some methods will work better than others in a particular situation.